Inae, who was falsely charged, is released from prison. Eunhye, her younger sister, is an 18-year-old high school student with the mental age of a ten-year-old. She adores her sister, who means the world to her. They get together for a small reunion party, and hope for nothing but happiness for them in the future.
Next day, however, Eunhye doesn’t return from school. Inae reports her missing to the police and asks her teacher for help, but no one seems to care about Eunhye’s whereabouts. Devastated by this tragedy, and by the society that doesn’t care for the weak, Inae embarks on an investigation all by herself.
She finds out that her sister suffered violence and sexual abuse from school bullies. Not only that, Eunhye has been passed on from a loan shark, to a massage parlor, then to someone else. Inae is hot on the trail and will not give up her quest to bring back Eunhye, but the path leads her to even more shocking secrets from her past: the owners of a convenience store, photo studio, and car repair shop all raped her a few years ago.
Now, it’s payback time! To console her sister, to find her, and to survive… Inae’s brutal revenge begins.